1. Field of the Invention
This invention relates to combustion control system for an engine, such as an internal combustion engine.
2. Description of the Prior Art
In internal combustion engines, when engine speed is low and engine load is small, swirls in intake air flow enhance combustion characteristics. At high engine speeds and great engine loads, high rates of intake air flow are necessary to achieve adequate engine power output.
Japanese Patent Publication No. 58-28529 discloses an air flow path control system for an internal combustion engine. This system has two air intake ports for each engine cylinder. The first port is designed to impart a swirl to the air flow. The second port allows a high air flow rate. At low engine speeds and small engine loads, a valve blocks the second port so that swirls are effectively developed in the air flow. At high engine speeds and great engine loads, the valve unblocks the second port so that air flows into the engine cylinder at a high rate substantially without swirling.